JSFiddle - React, Tailwind, and code Playground

HTML

<div data-value="a"></div>
<div data-value="b"></div>
<div data-value="c"></div>
<div data-value="d"></div>
<div data-value="a"></div>
<div data-value="d"></div>
<div data-value="e"></div>

JavaScript

var  tempArray = [];

$('div[data-value]').each(function(){
        var value = $(this).data("value");
        if($.inArray(value , tempArray) <= -1){
             tempArray.push(value);
        }
    });

console.log(tempArray);